The present invention relates to a method and apparatus for attaching a stud assembly to a relatively stationary object. More particularly, the invention relates to a method and apparatus for welding a stud to the stationary object and thereafter automatically advancing a prethreaded movable portion of the assembly to a final position.
Conventional stud welding is an extremely efficient and versatile fastening method. This technique has proven to be extremely beneficial in the metal working, transportation, and construction industries.
Stud welding is a process which is applicable to mild steel, stainless steel and aluminum. In the conventional process, an electric arc weld is utilized to bond the stud to the work piece. An electric arc is produced between the stud and the electrically conductive work piece and is maintained for a predetermined period. The heat produced by the electric arc forms a molten pool at the juncture of the stud and the work piece which, when permitted to cool, may be stronger than the stud itself.
It will be appreciated that the stud welding technique has an extremely broad spectrum of utility. For example, the technique is extensively utilized in the automotive, ship building, and building construction industries. The technique also finds utility in the furnace insulation industry.
A significant number of industrial furnaces operate at temperatures in excess of 2,500.degree. F. and over long periods of time. In order to prevent inefficient and expensive heat losses from such furnaces and to facilitate the protection of personnel in the vicinity of such furnaces, the furnace is lined with insulation. In the case of fiber insulation, rectangular blankets of insulating material may be attached to the interior of the furnace by means of a welded stud to which is fastened a member for holding the fiber insulation against the furnace wall.
In the past, fiber insulation has been used by Sauder Industries, Incorporated, Emporia, Kansas, to insulate high temperature furnaces. This insulation was attached by first welding a stud network to a wall of the furnace. Fiber blankets would then be impaled on the stud network in a manner to minimize undersirable compression in the fiber blanket and gaps at the joints between the blankets.
Many conventional procedures and apparatus for attaching blanket-type fiber insulation to the walls of a furnace may require uneconomical furnace downtime. In addition, extensive manpower may be required to first lay out the stud network, impale the insulating material over this network, and then affix the insulating blanket to the stud. Moreover, undesirable compression and gaps may occur in this procedure.
There is presently available in the industry a PYROBLOC brand insulation module into which there has been embedded a stud assembly. This stud assembly is comprised of a stud having an arc shield disposed at one end with a nut threaded onto the stud at the other end. Typically, a washer lies intermediate the arc shield and the nut and a tubular sleeve is interference fit over the nut. This stud assembly is operably disposed in such a manner as to firmly secure the insulation module to a wall of a furnace. When the stud portion of the stud assembly has been welded to the furnace wall, and the sleeve has been rotated to thread the nut against the washer, the arrangement serves to secure the module to the furnace wall.
Whereas the method and apparatus of the present invention may have a large variety of applications, it will be seen that a particularly useful application of the present invention is the affixing of PYRO-BLOC brand insulation material to the walls of a furnace in an improved and significantly more economical manner over prior art techniques and apparatus.